The use of mesenchymal stem cells (MSC) for clinically-relevant treatments of disorders including spinal cord injury (SCI) is supported by experimental data indicating that MSC modulate inflammatory reactions, scar tissue formation, and paracrine actions on resident cells. A main objective of these studies is to determine whether the anti-inflammatory benefit of MSC requires their presence in the injury site or can be achieved through microscopic bioreactors implanted in a more accessible location (i.e. lumbar enlargement of the spinal cord) and mediated by secreted factors delivered into the CSF. Although evidence suggests that MSC can modulate the environment in the injured spinal cord to limit tissue damage, it is likely that additional factors need to be provided for more extensive functional recovery, including axonal regeneration. Therefore, an objective of this study is to investigate the effects of encapsulated MSC alone and in combination with neural stem/precursor cell implantation in reducing inflammation, and increasing axonal extension and functional recovery, as a potential (sub)-acute SCI treatment. Toward these goals, we will pursue three aims. 1. To develop an efficient method of MSC encapsulation. We will utilize alginate-poly L-lysine-alginate MSC micro-encapsulation to promote cell viability and secretion of anti-inflammatory agents. We expect that these studies will yield a novel MSC encapsulation technique that will sustain MSC viability and function in vitro, and which can be used to generate implantable MSC bioreactors for transplantation experiments in SCI. 2. To analyze immunomodulatory effects of MSC. Freely migrating and encapsulated MSC will be injected into the lumbar enlargement to gain access to the CSF, and their distribution and viability will be analyzed over time. Changes in mRNA and protein expression in and around the injury site will be analyzed in tissue extracts. 3. To combine the immunomodulatory effects of MSC in SCI with neural stem/precursor cells. We will explore lumbar puncture administration as a clinically-relevant approach for combination treatment of MSC with other cells. The effects of MSC on endogenous neural stem/precursor cells will be analyzed histologically. We will also transplant neural stem/precursor cells into SCI in combinations with MSC to analyze whether modulation of the injured spinal cord environment can facilitate the action of other cells. As a result of the studies described above, we expect to: i) develop an implantable MSC bioreactor, ii) compare the effect of encapsulated and migrating MSCs in promoting tissue recovery after SCI, iii) compare the effect of human and rat MSC in SCI, and iv) evaluate potential synergistic or complementary effects of MSC and neural stem/precursor cell infusion in a widely used rat SCI model, which eventually will facilitate testing in large animal models and humans. The studies described here will use a clinically-relevant method of delivering MSC to the spinal cord that will create a better understanding of the capabilities of MSC as anti-inflammatory agents for SCI treatment alone and in combination with other cells. PUBLIC HEALTH RELEVANCE: We will investigate the anti-inflammatory effects of human and rat bone marrow mesenchymal stem cells (MSC) for clinically-relevant treatments of acute spinal cord injury (SCI) by introducing these cells through less invasive procedures that do not require surgery but resemble a spinal tap. We will also test enclosing the cells in alginate capsules that prevent them from getting rejected. The combined approach may open widely applicable and less invasive treatments for early intervention after spinal cord injury with partially matched MSC that can be stored in frozen cell banks.